To find the surface area of the pyramid, we need to find the area of each face and then add them together.
The base of the pyramid is a triangle with a side length of 4.5 cm and a height of 3.9 cm. The area of the base is (1/2) * base * height = (1/2) * 4.5 cm * 3.9 cm = 8.775 cm².
The lateral faces of the pyramid are three congruent triangles. The base of each triangle is the same as the base of the pyramid (4.5 cm), and the height of each triangle is 3.5 cm. The area of each lateral face is (1/2) * base * height = (1/2) * 4.5 cm * 3.5 cm = 7.875 cm².
There are three lateral faces, so the total area of the lateral faces is 3 * 7.875 cm² = 23.625 cm².
To find the surface area of the pyramid, we add the area of the base and the area of the lateral faces: 8.775 cm² + 23.625 cm² = 32.4 cm².
Therefore, the surface area of each pyramid is 32.4 cm².